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Political views are often so staunchly held that one wonders whether they aren't hardwired in a person's genes. Indeed, in the past, studies of twins have suggested that DNA may play a role in determining political attitudes. Although no one has yet discovered a gene for, say, supporting the war in Iraq, a small new study by political scientists at the University of NebraskaLincoln and other institutions reports another association between a person's biology and his politics.

The study, published in the Sept. 19 issue of the journal Science, involved 46 Nebraska residents with strong political convictions. Researchers examined the link between each participant's stated political views and his or her physiological response to a perceived threat in the lab. People with stronger measurable threat responses, the study found, tended to adhere to "socially protective" political policies, or those that suggest more concern for preserving the social unit  for example, supporting the Iraq war and the death penalty but opposing abortion rights and gay marriage.

Researchers shied away from using labels such as conservative and liberal in their study, but they concede that volunteers who registered a heightened sense of threat also tended to subscribe to conservative attitudes. "It's not that conservatives are 'fraidy-cats," says Kevin Smith, a political science professor at the University of NebraskaLincoln and one of the study's co-authors. "It's that people who support socially protective policies  which, yes, can be interpreted as people taking a conservative position on those policies  are more sensitive to environmental threat."

To measure that sensitivity, researchers conducted two tests. In one, they showed volunteers a series of photos that included some threatening images  for example, a picture of a man with a spider on his face or an infected open wound  while measuring the electrical conductance of the volunteers' skin, a technique also used in polygraph testing. In a separate experiment, researchers subjected the volunteers to sudden bursts of loud white noise to test their startle reflexes, measured by sensors attached to the muscle below the eye that recorded how hard people blinked.

People who blinked harder than others and registered a heightened response to threat on the conductivity test tended to support the death penalty and military spending. People with a mellower startle response were more likely to support abortion rights and gun control. The study also looked at several broader political tendencies, including compromise (the willingness to yield to a middle-ground solution) and obedience (the tendency to follow a set path), and found that people who were more sensitive to threat were less amenable to the former and more inclined toward the latter.

The study's authors are quick to point out that these correlations won't necessarily apply across the board and that the findings don't imply that people take political positions out of fear. (Fear, of course, is not a bad thing  a certain amount of it is necessary for survival.) The point, rather, is that there may be something fundamentally biological about politics.

"The reason that we have differences in political attitudes may be because deep down we have real differences, and we react to the world and see the world in different ways," says Smith. The study, he says, "basically confirms what people intuitively know about politics: a lot of it comes from the gut. We feel it on a really deep, probably biological basis, at least to some extent."

Physiology could help explain why people are so resolute, often infuriatingly, in their political views. Says John Hibbing, another co-author of the study and a professor at the University of NebraskaLincoln: "We need to maybe recognize that we're not going to cause our political opponents at some point to kind of break down, head in hand, Perry Masonstyle and say that they're wrong. They just see the world differently; they feel it differently."

But that doesn't mean compromise is out of the question  physiological factors are far from deterministic. Besides, a simple acknowledgement of the correlation between people's physiology and their politics could perhaps encourage a more forbearing kind of political discourse. Red and blue may never meet, but as Hibbing says, "I've got this naive hope that maybe we would actually be a little bit more understanding of people on the other side of the political aisle."